Techniques and equipment are now available for direct culturing of the sinuses and of the lower respiratory tract, for preparation of microbial antigens and for delineation of the mechanisms of allergic reactivity. Appropriate patients are available to our group for such an intensive study. The purpose of the proposed study is to identify and compare the microorganisms present in the sinuses and in the lower respiratory tract of patients with chronic bronchitis associated with bronchospasm and to characterize the dermal reactivity (i.e., reagin, Arthus or tuberculin-type delayed responses) to antigenic fractions of these microorganisms in such patients. A special effort will be made to learn: 1) the possible role of an isolated lack of an immune mechanism against usually nonpathogenic organisms in perpetrating chronic sinotracheobronchitis in some patients with or without hyperractive airways: 2) if tissue damage and/or bronchospasm associated with chronic bronchitis can sometimes be due to an immunologic mechanism: 3) If an immunologic mechanism is involved in some cases, which of several mechanisms is operative and 4) if a spcific strain of organism, even organisms currently classified as nonpathogenic, will elicit allergic reactions in certain patients with chronic bronchitis which are not observed when the same organism is tested on other subjects with chronic bronchitis. BIBLIOGRAPHIC REFERENCES: Schumacher, M.J., McClatchy, J.K., Farr, R.S. and Minden, P: Primary interaction between antibody and components of Alternaria. 1. Immunological and chemical characteristics of labeled antigens. J. Allergy Clin. Immunol. 56:39-53, 1975. Schumacher, M.J., Farr, R.S., McClatchy, J.K. and Minden, P.: Primary interaction between antibody and components of Alternaria. II. Antibodies in sera from normal, allergic, and immunoglobulin-deficient children. J. Allergy Clin. Immunol. 56:54-63, 1975.